Aqueous ink jet inks containing ester diol and amide diol cosolvents

ABSTRACT

An ink for ink jet printers which comprises an aqueous carrier medium, pigment dispersion or dye and an amide diol or ester diol cosolvent penetrant such as hydroxypivalyl hydroxypivalate. The cosolvent penetrant has a solubility in water of at least 4.5 parts in 100 parts of water at 25° C. 
     The pigment dispersion consists of pigment particles and a dispersant, preferably a polymeric dispersant, having a hydrophilic segment and a segment that links to the pigment. These inks exhibit rapid drying, have excellent decap performance, are storage stable and give images having good print quality.

FIELD OF THE INVENTION

This invention relates to aqueous inks for ink jet printers, and, moreparticularly, to aqueous, colored inks containing ester diols or amidediols as cosolvents.

BACKGROUND OF THE INVENTION

Ink jet printing is a non-impact process in which an electronic signalproduces droplets of ink that are deposited on a substrate such as paperor transparent film. Ink jet printers are broadly utilized as output forpersonal and other computers due to their reliability, print quality,low cost, relatively quiet operation and their graphics capability.Thermal or bubble jet drop-on-demand printers have been especiallysuccessful and are widely used in office, industrial and home sites.

A major concern with all ink jet printing devices is pluggage of nozzlesduring operation and between operations. A critical property for an inkjet ink is the decap time which is the length of time over which an inkremains fluid in a pen opening when exposed to air and therefore capableof firing a drop of ink at its intended target. Failure is often due toevaporation of solvent causing precipitation or crystallization of asolid at the air/liquid interface. In pigmented inks a further cause ofpluggage is the flocculation of dispersed pigment due to a change insolvent composition caused by evaporation.

As evaporation proceeds an initial increase in viscosity may affect inkperformance. As solid material begins to form the projected ink dropsmay be deflected from their intended trajectory or even worse maycompletely plug nozzles thereby causing total print failure. In amultinozzle printer, certain nozzles are assigned to infrequently usedcharacters and these are the most likely to undergo pluggage failure.Also a series of nozzles must be able to start printing after a periodof non-use.

A further complicating factor is the use of heating devices toaccelerate ink drying on the paper. This also accelerates solventevaporation in the nozzle and makes pluggage more likely.

A second critical ink property is the ability to penetrate paper or filmrapidly so as to allow for rapid drying. One major deficiency of thermalink jet printers is their relatively slow printing speed compared toprinters using competing technologies. A major obstacle is the inkdrying rate. In a sheet fed printer, the ink must be dry before thesucceeding sheet contacts it or the ink will smear. This is the majorfactor affecting printer productivity. Rapid drying by penetration is analternate to using a heater to increase drying. Use of a heaterincreases the purchase price of the printer.

The use of penetrants or cosolvents is known in the art as a means toincrease the rate of penetration of inks. However, the known penetrants,such as Butyl Carbitol®, have unacceptable or marginally acceptabledecap times and cause pigment dispersions to flocculate.

A third important requirement for inks where the colorant is a pigmentis for the pigment dispersion to remain stable throughout the life ofthe ink jet cartridge. Dye-based ink jet inks suffer from deficienciesin water fastness, smear fastness and lightfastness. Therefore pigmentsare a preferred alternative to dyes provided the pigment dispersions canbe made stable to flocculation and settling. Many commonly usedcosolvents cause destabilization of pigment dispersions and cannot beused either as penetrants or pluggage inhibitors.

These three requirements, pluggage inhibition, rapid media penetrationand compatibility with pigment dispersions are often in conflict.Therefore it is difficult to obtain all three useful properties in asingle substance. Rapid penetrants are mediocre or poor pluggageinhibitors. Pluggage inhibitors make poor penetrants. Both pluggageinhibitors and rapid penetrants are usually destabilizing toward pigmentdispersions. Accordingly, a need exists for cosolvents that decreasedrying time and increase decap time without destabilizing pigment-basedinks.

This invention allows pigmented inks to have rapid dry time and longdecap times without compromising pigment dispersion stability.

SUMMARY OF THE INVENTION

In accordance with this invention there is provided an aqueous ink jetink composition comprising:

(a) an aqueous carrier medium,

(b) a pigment dispersion or dye; and

(c) an ester or amide diol compound having a solubility in water of atleast 4.5 parts in 100 parts of water at 25° C. and represented by theformula: ##STR1## wherein R'=--CH₃, --C₂ H₅, --C₃ H₇, or --C₄ H₉ and

R"=--CH₃, --C₂ H₅, or --C₃ H₇ and

X=O or N--Y wherein Y=H, CH₃, CH₂ CH₃ or CH₂ CH₂ OH.

The inks of the invention are rapid drying, have superior decapperformance, are extremely stable, have low viscosity, exhibit excellentprint quality, and provide excellent water and smear resistance afterdrying. They may be used with a variety of ink jet printers such ascontinuous, piezoelectric, drop-on-demand and thermal or bubble jetdrop-on-demand, and are particularly adapted for use in thermal ink jetprinters.

DETAILED DESCRIPTION OF THE INVENTION

The invention relates to an ink jet ink composition which isparticularly suited for use in ink jet printers in general, and thermalink jet printers in particular. The ink jet ink composition encompassesboth pigment-based inks and dye-based inks. The pigmented inks comprisean aqueous carrier medium, an ester diol or amide diol cosolvent and apigment dispersion which is an aqueous dispersion of pigment particles,stabilized by dispersants, usually polymeric, that are stable over longperiods, both in storage and in the printer. The dye-based inks comprisean aqueous carrier medium, a dye and an ester diol or amide diolcosolvent. The inks may be adapted to the requirements of a particularink jet printer to provide a balance of light stability, smearresistance, viscosity, surface tension, high optical density, and crustresistance.

The aqueous carrier comprises water or a mixture of water and an organicwater soluble compound other than the ester diol or amide diol compound.

A major advantage of using the cosolvents described in this invention istheir compatibility with pigment dispersions. However, the cosolventscan also be used in dye-based inks to impart rapid penetration ofaqueous dye-based inks into the paper.

ESTER DIOL OR AMIDE DIOL COSOLVENT OR PENETRANTS

The compounds of this invention fill a need for pigmented ink jet inkswith good dispersion stability in the presence of a cosolvent thatimparts both rapid media penetration and long decap performance.

The ester diol or amide diol compounds of the invention have asolubility in water of at least 4.5 parts in 100 parts of water at 25°C. and are represented by the formula: ##STR2## wherein R'=--CH₃, --C₂H₅ , --C₃ H₇, or --C₄ H₉ and

R"=--CH₃, --C₂ H₅, or --C₃ H₇ and

X=O for an ester diol or

N--Y for an amide diol wherein Y=H, CH₃, CH₂ CH₃ or CH₂ CH₂ OH.

Preferred are ester diols, and more specifically hydroxypivalylhydroxypivalate also known as neopentyl glycol hydroxypivalate and isrepresented by the formula: ##STR3##

DISPERSANTS

The pigment dispersion comprises a pigment and usually a dispersant.Preferably, the dispersant is a polymeric dispersant. In addition to, orin place of a polymeric dispersant surfactant compounds may be used asdispersants. These may be anionic, cationic, nonionic or amphoteric. Adetailed list of non-polymeric as well as some polymer dispersants arelisted in the section on dispersants, pages 110-129, 1990 McCutcheon'sFunctional Materials, North American Edition, Manufacturing ConfectionPublishing Co., Glen Rock, N.J. 07452.

POLYMERIC DISPERSANTS

Polymeric dispersants suitable for practicing the invention include ABor BAB block copolymers wherein the A block is hydrophobic and serves tolink with the pigment, and the B block is hydrophilic and serves todisperse the pigment in the aqueous medium. Selection of the polymer fora specific application will depend on the selected pigment and aqueousmedium. In general, the polymer is an AB or BAB block copolymer wherein(a) the A segment is a hydrophobic homopolymer or copolymer of anacrylic monomer having the formula:

    CH.sub.2 ═C(X)(Y)

wherein X is H or CH₃ ; and Y is C(O)OR₁, C(O)NR₂ R₃, or CN, wherein R₂is an alkyl, aryl, or alkylaryl group having 1 to 20 carbon atoms, andR₂ and R₃ are hydrogen or an alkyl, aryl, or alkylaryl group having 1 to9 carbon atoms; said A segment having an average molecular weight of atleast approximately 300 and being water insoluble; and (b) the B segmentis a hydrophilic polymer, or salt thereof, of

(1) an acrylic monomer having the formula:

    CH.sub.2 ═C(X)(Y1)

wherein X is H or CH₃ ; and Y₁ is C(O)OH, C(O)NR₂ R₃, C(O)OR₄ NR₂ R₃ orC(OR₅); wherein R₂ and R₃ are hydrogen or an alkyl, aryl, or alkylarylgroup having 1 to 9 carbon atoms; R₄ is an alkyl diradical having 1 to 5carbon atoms; and R₅ is an alkyl group having 1 to 20 carbon atoms andoptionally containing one or more hydroxyl or ether groups; or

(2) a copolymer of the acrylic monomer of

(1) with an acrylic monomer having the formula:

    CH.sub.2 ═C(X)(Y)

where X and Y are the substituent groups defined for the A segment; theB segment having an average molecular weight of at least approximately300 and being water soluble. The B block(s) generally will constitute 10to 90%, preferably 25 to 65%, of the entire block polymer by weight.

The A block is a polymer or copolymer prepared from at least one acrylicmonomer having the formula set forth above. The R₁, R₂ and R₃ groupsoptionally may contain hydroxy, ether, OSi(CH₃)₃ groups, and similarsubstituent groups. Representative monomers that may be selectedinclude, but are not limited to, the following: methyl methacrylate(MMA), ethyl methacrylate (EMA), propyl methacrylate, n-butylmethacrylate (BMA or NBMA), hexyl methacrylate, 2-ethylhexylmethacrylate (EHMA), octyl methacrylate, lauryl methacrylate (LMA),stearyl methacrylate, phenyl methacrylate, benzyl methacrylate,hydroxyethyl methacrylate (HEMA), hydroxypropyl methacrylate,2-ethoxyethyl methacrylate, methacrylonitrile, 2-trimethylsiloxyethylmethacrylate, glycidyl methacrylate(GMA), p-tolyl methacrylate, sorbylmethacrylate, methyl acrylate, ethyl acrylate, propyl acrylate, butylacrylate, hexyl acrylate, 2-ethylhexyl acrylate, octyl acrylate, laurylacrylate, stearyl acrylate, phenyl acrylate, benzyl acrylate,hydroxyethyl acrylate, hydroxypropyl acrylate, acrylonitrile,2-trimethyl-siloxyethyl acrylate, glycidyl acrylate, p-tolyl acrylate,and sorbyl acrylate. Preferred A blocks are homopolymers and copolymersprepared from methyl methacrylate, butyl methacrylate, 2-ethylhexylmethacrylate, or copolymers of methyl methacrylate with butylmethacrylate.

The A block also may contain a hydrophilic monomer such as CH₂═C(X)(Y)', wherein X is H or CH₃ and Y' is C(O)OH, C(O)NR₂ R₃, C(O)OR₄NR₂ R₃, C(OR₅), or their salts, wherein R₂ and R₃ may be H or C1 to C9alkyl, aryl, or alkylaryl, R₄ is a C1 to C5 alkyl diradical, and R₅ is aC1 to C20 alkyl diradical which may contain hydroxy or ether groups, toprovide some changes in solubility. However, there should not be enoughhydrophilic monomer present in the A block to render it, or its salt,completely water soluble.

The B block is a polymer prepared from at least one acrylic monomerhaving the formula provided above. Representative monomers includemethacrylic acid (MAA), acrylic acid, dimethylaminoethyl methacrylate(DMAEMA), diethylaminoethyl methacrylate, t-butylaminoethylmethacrylate, dimethylaminoethyl acrylate, diethylaminoethyl acrylate,dimethylaminopropyl methacrylamide, methacrylamide, acrylamide, anddimethylacrylamide. Homopolymers or copolymers of methacrylic acid ordimethylaminoethyl methacrylate are preferred.

The acid containing polymer may be made directly or may be made from ablocked monomer with the blocking group being removed afterpolymerization. Examples of blocked monomers that generate acrylic ormethacrylic acid after removal of the blocking group include:trimethylsilyl methacrylate (TMS-MAA), trimethylsilyl acrylate,1-butoxyethyl methacrylate, 1-ethoxyethyl methacrylate, 1-butoxyethylacrylate, 1-ethoxyethyl acrylate, 2-tetrahydropyranyl acrylate, and2-tetrahydropyranyl methacrylate.

The B block may be a copolymer of an acid or amino containing monomerwith other monomers, such as those used in the A block. The acid oramino monomer may be used in a range of 10 to 100%, preferable in arange of 20 to 100%, of the B block composition. The B block(s)generally will constitute 10 to 90%, preferably 25 to 65%, of the entireblock polymer by weight.

Block copolymers that are useful in practicing the invention have anumber average molecular weight below 20,000, preferably below 15,000,and typically in the range of 1,000 to 3,000. Preferred block copolymershave number average molecular weights in the range of 500 to 1500 foreach A and B block.

Representative AB and BAB block polymers that may be selected includethe following, wherein the values recited represent the degree ofpolymerization of each monomer. A double slash indicates a separationbetween blocks and a single slash indicates a random copolymer. Forexample, MMA//MMA/MMA 10//5/7.5 is an AB block polymer with an A blockof MMA that is 10 monomer units long, molecular weight of 1000 and a Bblock that is a copolymer of MMA and MAA with 5 monomer units of MMA and7.5 units of MAA; molecular weight of the B block is 1145.

    ______________________________________                                        AB BLOCK POLYMER      MOL. WEIGHT                                             ______________________________________                                        EHMA//EHMA/MAA                                                                3//3/5                1618                                                    5//2.5/2.5            1700                                                    5//5/10               2840                                                    20//10/10             6800                                                    15//11/22             7040                                                    EHMA//LMA/MAA                                                                 10//10/12             5552                                                    EHMA//MMA/EHMA/MAA                                                            10//5/5/12            4502                                                    EHMA//MMA/MAA                                                                 5//5/10               2350                                                    5//10/10              2850                                                    EHMA//MAA                                                                     15//5                 3400                                                    BMA//BMA/MAA                                                                  5//2.5/2.5            1280                                                    10//5/10              3000                                                    20//10/20             6000                                                    15//7.5/3             3450                                                    5//5/10               2300                                                    5//10/5               2560                                                    BMA//MMA/MAA                                                                  15//15/5              4060                                                    15//7.5/3             3140                                                    10//5/10              2780                                                    MMA//MMA/MAA                                                                  10//5/10              2360                                                    10//5/5               1930                                                    10//5/7.5             2150                                                    20//5/7.5             3150                                                    15/7.5/3              2770                                                    MMA/EHMA/MAA                                                                  5//5/10               2350                                                    10//5/10              2850                                                    BMA/MMA//BMA/MAA                                                              5/5//5/10             2780                                                    BMA//MAA                                                                      10//10                2260                                                    BMA//HEMA/MAA                                                                 15//7.5/3             3360                                                    7.5//7.5/3            2300                                                    15//7.5/7.5           3750                                                    BMA//BMA/DMAEMA                                                               10//5/10              3700                                                    BMA//BMA/DMAEMA/MAA                                                           10//5/5/5             2635                                                    BAB BLOCK POLYMER                                                             BMA/MAA//BMA//BMA/MAA                                                         5/10//10//5/10        4560                                                    MMA/MAA//MMA//MMA/MAA                                                         5/7.5//10//5/7.5      3290                                                    ______________________________________                                    

Preferred block polymers are methyl methacrylate//methylmethacrylate/methacrylic acid (10//5/7.5), 2-ethylhexylmethacrylate//2-ethylhexyl methacrylate/methacrylic acid (5//5/10),n-butyl methacrylate//n-butyl methacrylate/methacrylic acid (10//5/10),n-butyl methacrylate//methacrylic acid (10//10)), ethylhexylmethacrylate//methyl methacrylate/methacrylic acid (5//10/10),n-butyl-methacrylate//2-hydroxyethyl methacrylate/methacrylic acid(5//10/10), n-butylmethacrylate//2-hydroxyethyl methacrylate/methacrylicacid (15//7.5/3), methyl methacrylate//ethylhexylmethacrylate/methacrylic acid (5//5/10), and butyl methacrylate//butylmethacrylate/dimethylaminoethyl methacrylate (10//5/10).

To solubilize the B block into the aqueous medium, it may be necessaryto make salts of either the acid or amino groups contained in the Bblock. Salts of the acid monomers can be made with the counter componentbeing selected from organic bases such as mono-, di-, tri-methylamine,morpholine, n-methyl morpholine; alcohol amines such asdimethylethanolamine (DMEA), methyldiethanolamine, mono-, di-, andtri-ethanolamine; pyridine; ammonium hydroxide; tetra-alkylammoniumsalts such as tetramethylammonium hydroxide, tetraethylammoniumhydroxide; alkali metals such as lithium, sodium and potassium, and thelike. Preferred neutralizing agents include dimethylethanolamine andsodium and potassium hydroxides, with potassium hydroxide beingparticularly preferred for inks to be used in thermal ink jet printers.Salts of the amino monomers can be made with the counter component beingselected from organic acids such as acetic acid, formic acid, oxalicacid, dimethylol propionic acid, halogens such as chloride, fluoride,and bromide, and other inorganic acids, such as sulfuric acid, nitricacid, phosphoric acid and the like. It is also possible to convert theamino group into a tetra-alkyl ammonium salt. Amphoteric polymers, thatis polymer that contains both an acid group and an amino group, may beused as is or can be neutralized with either addition of acid or base.

The AB and BAB polymers can be advantageously produced by a stepwisepolymerization process such as anionic or group transfer polymerizationas described in Webster, U.S. Pat. No. 4,508,880, the disclosure ofwhich is incorporated herein by reference. Polymers so produced haveprecisely controlled molecular weight, block sizes and very narrowmolecular weight distributions. The polymer typically has a dispersityless than 2, generally in the range of 1.0 to 1.4. Dispersity is thepolymer weight average molecular weight divided by its number averagemolecular weight. Number average molecular weight can be determined bygel permeation chromatography (GPC). The AB or BAB block polymers mayalso be formed by free radical polymerization wherein the initiationunit is comprised of two different moieties which initiatepolymerization at two distinctly different temperatures. However, thismethod may cause contamination of the block copolymers with homopolymerand coupled products.

The AB block polymers also may be prepared using conventional anionicpolymerization techniques, in which a first block of the copolymer isformed, and upon completion of the first block, a second monomer streamis started to form a subsequent block of the polymer. A low reactiontemperature, e.g., 0° to -70° C., is maintained in this case to minimizeside reactions and form blocks of the desired molecular weights.

With many of these techniques, and especially with the group transferpolymerization process, the initiator may be non-functional, may containan acid group (used as is or in a blocked form) or may contain an aminogroup. Either the hydrophobic A block or the hydrophilic B block may bemade first. The BAB block polymers also may be prepared by anionicpolymerization or group transfer polymerization techniques by firstpolymerizing one of the B Blocks, then polymerizing the hydrophobic Ablock, and then polymerizing the second B Block.

Random copolymers can be used as dispersants although they are not aseffective in stabilizing pigment dispersions. Amongst these may bementioned half-esters of maleic acid/styrene copolymers, ligninsulfonate derivatives and copolymers of acrylic and methacrylic acidwith styrene.

COLORANTS

Colorants useful in practicing the invention comprise both pigments anddyes.

Pigments

Amongst pigments, a wide variety of organic and inorganic pigments,alone or in combination, may be selected to make the ink. The term"pigment" as used herein means an insoluble colorant. The pigmentparticles are sufficiently small to permit free flow of the ink throughthe ink jet printing device, especially at the ejecting nozzles thatusually have a diameter ranging from 10 micron to 50 micron. Theparticle size also has an influence on the pigment dispersion stability,which is critical throughout the life of the ink. Brownian motion ofminute particles will help prevent the particles from settling. It isalso desirable to use small particles for maximum color strength. Therange of useful particle size is approximately 0.005 micron to 15micron. Preferably, the pigment particle size should range from 0.005 to5 micron, next preferably from 0.01 to 1 micron and, most preferably,from 0.005 to 0.3 micron.

The selected pigment may be used in dry or wet form. For example,pigments are usually manufactured in aqueous media and the resultingpigment is obtained as water wet presscake. In presscake form, thepigment is not aggregated to the extent that it is in dry form. Thus,pigments in water wet presscake form do not require as muchdeaggregation in the process of preparing the inks from dry pigments.Representative commercial dry pigments that may be used in practicingthe invention include the following:

    ______________________________________                                                                      Pigment                                         Pigment Brand Name Manufacturer                                                                             Color Index                                     ______________________________________                                        Permanent Yellow DHG                                                                             Hoechst    Yellow 12                                       Permanent Yellow GR                                                                              Hoechst    Yellow 13                                       Permanent Yellow G Hoechst    Yellow 14                                       Permanent Yellow NCG-71                                                                          Hoechst    Yellow 16                                       Permanent Yellow GG                                                                              Hoecsht    Yellow 17                                       Hansa Yellow RA    Hoechst    Yellow 73                                       Hansa Brilliant Yellow 5GX-02                                                                    Hoechst    Yellow 74                                       Dalamar ® Yellow YT-858-D                                                                    Heubach    Yellow 74                                       Hansa Yellow X     Hoechst    Yellow 75                                       Novoperm ® Yellow HR                                                                         Hoechst    Yellow 83                                       Chromophtal ® Yellow 3G                                                                      Ciba-Geigy Yellow 93                                       Chromophtal ® Yellow GR                                                                      Ciba-Geigy Yellow 95                                       Novoperm ® Yellow FGL                                                                        Hoechst    Yellow 97                                       Hansa Brilliant Yellow 10GX                                                                      Hoechst    Yellow 98                                       Permanent Yellow G3R-01                                                                          Hoechst    Yellow 114                                      PV Fast Yellow H2G-01                                                                            Hoechst    Yellow 120                                      Chromophtal ® Yellow 8G                                                                      Ciba-Geigy Yellow 128                                      Irgazin ® Yellow 5GT                                                                         Ciba-Geigy Yellow 129                                      Hostaperm@ Yellow H4G                                                                            Hoechst    Yellow 151                                      Hostaperm@ Yellow H3G                                                                            Hoechst    Yellow 154                                      Hostaperm@ Yellow H6G                                                                            Hoechst    Yellow 175                                      PV Fast Yellow HG  Hoechst    Yellow 180                                      L74-1357 Yellow    Sun Chem.                                                  L75-1331 Yellow    Sun Chem.                                                  L75-2377 Yellow    Sun Chem.                                                  Hostaperm ® Orange GR                                                                        Hoechst    Orange 43                                       Paliogen ® Orange                                                                            BASF       Orange 51                                       Irgalite ® Rubine 4BL                                                                        Ciba-Geigy Red 57:1                                        Quindo ® Magenta                                                                             Mobay      Red 122                                         Indofast ® Brilliant Scarlet                                                                 Mobay      Red 123                                         Hostaperm ® Scarlet GO                                                                       Hoechst    Red 168                                         Permanent Rubine F6B                                                                             Hoechst    Red 184                                         Monastral ® Magenta                                                                          Ciba-Geigy Red 202                                         Monastral ® Scarlet                                                                          Ciba-Geigy Red 207                                         Heliogen ® Blue L 6901F                                                                      BASF       Blue 15:2                                       Heliogen ® Blue NBD 7010                                                                     BASF                                                       Heliogen ® Blue K 7090                                                                       BASF       Blue 15:3                                       Heliogen ® Blue L 7101F                                                                      BASF       Blue 15:4                                       Paliogen ® Blue L 6470                                                                       BASF       Blue 60                                         Heucophthal ® Blue G, XBT-583D                                                               Heubach    Blue 15:3                                       Heliogen ® Green K 8683                                                                      BASF       Green 7                                         Heliogen ® Green L 9140                                                                      BASF       Green 36                                        Monastral ® Violet R                                                                         Ciba-Geigy Violet 19                                       Monastral@  Red B  Ciba-Geigy Violet 19                                       Quindo ® Red R6700                                                                           Mobay      Violet 19                                       Quindo ® Red R6713                                                                           Mobay      Violet 19                                       Indofast ® Violet                                                                            Mobay      Violet 23                                       Monastral ® Violet Maroon B                                                                  Ciba-Geigy Violet 42                                       Monarch > 1400     Cabot      Black 7                                         Monarch > 1300     Cabot      Black 7                                         Monarch > 1100     Cabot      Black 7                                         Monarch > 1000     Cabot      Black 7                                         Monarch > 900      Cabot      Black 7                                         Monarch > 880      Cabot      Black 7                                         Monarch > 800      Cabot      Black 7                                         Monarch > 700      Cabot      Black 7                                         Raven 7000         Columbian  Black 7                                         Raven 5750         Columbian  Black 7                                         Raven 5250         Columbian  Black 7                                         Raven 5000         Columbian  Black 7                                         Raven 3500         Columbian  Black 7                                         Color Black FW 200 Degussa    Black 7                                         Color Black FW 2   Degussa    Black 7                                         Color Black FW 2V  Degussa    Black 7                                         Color Black FW 1   Degussa    Black 7                                         Color Black FW 18  Degussa    Black 7                                         Color Black S 160  Degussa    Black 7                                         Color Black S 170  Degussa    Black 7                                         Special Black 6    Degussa    Black 7                                         Special Black 5    Degussa    Black 7                                         Special Black 4A   Degussa    Black 7                                         Special Black 4    Degussa    Black 7                                         Printex U          Degussa    Black 7                                         Printex V          Degussa    Black 7                                         Printex 140U       Degussa    Black 7                                         Printex 140V       Degussa    Black 7                                         Tipure ® R-101 Du Pont    White 6                                         ______________________________________                                    

Representative commercial pigments that can be used in the form of awater wet presscake include: Heucophthal® Blue BT-585-P, Toluidine Red Y(C.I. Pigment Red 3), Quindo® Magenta (Pigment Red 122), Magenta RV-6831presscake (Mobay Chemical, Harmon Division, Haledon, N.J.), Sunfast®Magenta 122 (Sun Chemical Corp., Cincinnati, Ohio), Indo® BrilliantScarlet (Pigment Red 123, C.I. No. 71145), Toluidine Red B (C.I. PigmentRed 3), Watchung® Red B (C.I. Pigment Red 48), Permanent RubineF6B13-1731 (Pigment Red 184), Hansa® Yellow (Pigment Yellow 98),Dalamar® Yellow YT-839-P (Pigment Yellow 74, C.I. No. 11741, Sunbrite®Yellow 17 (Sun Chemical Corp, Cincinnati, Ohio), Toluidine Yellow G(C.I. Pigment Yellow 1), Pigment Scarlet (C.I. Pigment Red 60), AuricBrown (C.I. Pigment Brown 6), etc. Black pigments, such as carbon black,generally are not available in the form of aqueous presscakes.

Fine particles of metal or metal oxides also may be used to practice theinvention. For example, metal and metal oxides are suitable for thepreparation of magnetic ink jet inks. Fine particle size oxides, such assilica, alumina, titania, and the like, also may be selected.Furthermore, finely divided metal particles, such as copper, iron,steel, aluminum and alloys, may be selected for appropriateapplications.

Dyes

Dyes commonly used in aqueous ink jet inks include for example Acid,Direct, Food and Reactive dyes.

Amongst useful dyes there may be mentioned:

C.I. Food Blacks 1 and 2.

C.I. Acid Blacks 7, 24, 26, 48, 52, 58, 60, 107, 109, 118, 119, 131,140, 155, 156 and 187.

C.I. Direct Blacks 17, 19, 32, 38, 51, 71, 74, 75, 112, 117, 154, 163,and 168.

C.I. Acid Reds 1, 8, 17, 32, 35, 37, 42, 57, 92, 115, 119, 131, 133,134, 154, 186, 249, 254, and 256.

C.I. Direct Reds 37, 63 , 75, 79, 80, 83, 99, 220, 224 and 227.

C.I. Acid Violets 11, 34 and 75.

C.I. Direct Violets 47, 48, 51, 90 and 94.

C.I. Reactive Reds 4, 23, 24, 31 and 56.

C.I. Acid Blues 9, 29, 62, 102, 104, 113, 117, 120, 175 and 183.

C.I. Direct Blues 1, 6, 8, 15, 25, 71, 76, 78, 80, 86, 90, 106, 108,123, 163, 165, 199 and 226.

C.I. Reactive Blues 7 and 13.

C.I. Acid Yellows 3, 17, 19, 23, 25,, 29, 38, 49, 59, 61 and 72.

C.I. Direct Yellows 27, 28, 33, 39, 58, 86, 100 and 142.

C.I. Reactive Yellow 2.

AQUEOUS CARRIER MEDIUM

The aqueous carrier medium is water or a mixture of water and at leastone water soluble organic solvent other than the ester diol or amidediol cosolvent.

Deionized water is commonly used. Selection of a suitable mixture ofwater and water soluble organic solvent, depends on requirements of thespecific application, such as desired surface tension and viscosity, theselected pigment, drying time of the pigmented ink jet ink, and the typeof paper onto which the ink will be printed.

Representative examples of water-soluble organic solvents that may beselected include (1) alcohols, such as methyl alcohol, ethyl alcohol,n-propyl alcohol, iso-propyl alcohol, n-butyl alcohol, sec-butylalcohol, t-butyl alcohol, iso-butyl alcohol, furfuryl alcohol, andtetrahydrofurfuryl alcohol; (2) ketones or ketoalcohols such as acetone,methyl ethyl ketone and diacetone alcohol; (3) ethers, such astetrahydrofuran and dioxane; (4) esters, such as ethyl acetate, ethyllactate, ethylene carbonate and propylene carbonate; (5) polyhydricalcohols, such as ethylene glycol, diethylene glycol, triethyleneglycol, propylene glycol, tetraethylene glycol, polyethylene glycol,glycerol, 2-methyl-2,4-pentanediol, 1,2,6-hexanetriol and thiodiglycol;(6) lower alkyl mono- or di-ethers derived from alkylene glycols, suchas ethylene glycol mono-methyl (or -ethyl) ether, diethylene glycolmono-methyl (or -ethyl) ether, propylene glycol mono-methyl (or -ethyl)ether, triethylene glycol mono-methyl (or -ethyl) ether and diethyleneglycol di-methyl (or -ethyl) ether; (7) nitrogen containing cycliccompounds, such as pyrrolidone, N-methyl-2-pyrrolidone, and1,3-dimethyl-2-imidazolidinone; and (8) sulfur-containing compounds suchas dimethyl sulfoxide and tetramethylene sulfone.

A mixture of a water soluble organic solvent having at least 2 hydroxylgroups such as, diethylene glycol and water is preferred as the aqueouscarrier medium. In the case of a mixture of water, diethylene glycol andester diol or amide diol, the aqueous carrier medium plus ester diol oramide diol usually contains from about 30% water/70% solvent/ester diolor amide diol 5 mixture to about 95% water/5% solvent/ester diol oramide diol mixture. The preferred ratios are approximately 60% water/40%solvent/ester diol or amide diol mixture to about 95% water/5%solvent/ester diol or amide diol mixture. The solvent/ester diol oramide diol mixture contains 15-95% ester diol or amide diol, preferrably25-75%.

Percentages are based on the total weight of the aqueous carrier mediumplus ester diol or amide diol cosolvent.

OTHER INGREDIENTS

The ink may contain other ingredients. For example, surfactants may beused to alter surface tension as well as promote penetration. However,they may also destabilize pigmented inks. Surfactants may be anionic,cationic, amphoteric or nonionic. Useful surfactants may be selectedfrom McCutcheon's Emulsifiers and Detergents, published by ManufacturingConfectioners Publishing Company, Glen Rock, N.J. The choice ofsurfactant is highly dependent on the type of paper to be printed. It isexpected that one skilled in the art can select the appropriatesurfactant for the specific paper to be used in printing.

For example, the following surfactants were found to be useful inprinting on Gilbert Bond paper (25% cotton) designated type 1057manufactured by Mead Company, Dayton, Ohio.

    ______________________________________                                        Supplier and Tradename                                                                          Description                                                 ______________________________________                                        Air Products                                                                  Surfynol ® 465H                                                                             Ethoxylated Tetramethyl                                                       Decynediol                                                  Surfynol ® CT-136                                                                           Acethylenic diol,                                                             Anionic Surfactant                                                            Blend                                                       Surfynol ® GA Acetylenic Diol Blend                                       Surfynol ® TG Acetylenic Diol Blend                                                         in Ethylene Glycol                                          Cyanamid                                                                      Aerosol ® OT  Dioctyl Ester of Sodium                                                       Sulfosuccinic Acid                                                            Aerosol ® MA-80                                                           Dihexyl Ester of                                                              Sodium Sulfosuccinic                                                          Acid Aerosol ® MA-                                                        80/Aerosol OT 2/1                                           Du Pont                                                                       Duponol ® RA  Fortified Sodium Ether-                                                       Alcohol Sulfate                                             Merpol ® A    Ethylene Oxide, Ester                                                         Condensate                                                  Merpol ® LF-H Polyether                                                   Merpol ® SE   Alcohol Ethoxylate                                          Merpol ® SH   Ethylene Oxide Condensate                                   Zelec ® NK    Alcohol Phosphate                                                             Composition                                                 Fisher Scientific                                                             Polyethylene Glycol 3350                                                      Polyethylene Glycol 400                                                       Polyethylene Glycol 600                                                       ICI                                                                           Renex ® 30    Polyoxyethylene C 127                                                         Tridecyl Ether                                              Synthrapol ® KB                                                                             Polyoxyethylene Alkyl                                                         Alcohol                                                     Rohm & Haas                                                                   Triton ® CF 10                                                                              Alkylaryl Polyether                                         Triton ® CF 21                                                                              Alkylaryl Polyether                                         Triton ® N 111                                                                              Nonylphenoxy                                                Triton ® X-100                                                                              Polyethoxy Ethanol                                          Triton ® X-102                                                                              Octylphenoxy                                                                  Polyethoxy                                                                    Ethanol                                                     Triton ®  X-114                                                                             Octylphenoxy                                                                  Polyethoxy                                                                    Ethanol                                                     Union Carbide                                                                 Silwet ® L-7600                                                                             Polyalkyleneoxide                                                             Modified                                                    Silwet ® L-7607                                                                             Polyalkyleneoxide                                                             Modified                                                    Polydimethylsiloxane                                                                            Polyalkyleneoxide                                           Silwet ® L-7607                                                                             Modified                                                    Polydimethylsiloxane                                                                            Polyalkyleneoxide                                           Silwet ® L-77 Modified                                                    Polydimethylsiloxane                                                                            Polyalkylene Glycol                                         UCON ® ML1281                                                             W. R. Grace                                                                   Hampshire Div.,   Lauryoyl                                                    Hamposyl ® Lida                                                                             Iminodiacetic                                                                 Acid.                                                       ______________________________________                                    

In aqueous inks, the surfactants may be present in the amount of 0.01-5%and preferably 0.2-2%.

Biocides may be present to inhibit growth of anisms. Dowicides (DowChemical, Midland Mich. 48674) Omidines® (Olin Corp, Cheshire, Conn.06410), Nopcocides (Henkel Corp, Ambler, Pa. 19002) Troysans (TroyChemical Corp., Newark N.J. 17105) and sodium benzoate may be used.

In addition, sequestering agents such as EDTA may also be included toeliminate deleterious effects of heavy metal impurities.

INK PREPARATION

The pigmented ink is prepared by premixing the selected pigment(s) anddispersant in water. In the case of dyes some of the same factors applyexcept that there is no dispersant present and no need for pigmentdeaggregation. The dye-based ink is prepared in a well agitated vesselrather than in dispersing equipment. Cosolvents and ester diols or amidediols may be present during the dispersion.

The dispersing step may be accomplished in a horizontal mini mill, aball mill, an attritor, or by passing the mixture through a plurality ofnozzles within a liquid jet interaction chamber at a liquid pressure ofat least 1000 psi to produce a uniform dispersion of the pigmentparticles in the aqueous carrier medium.

It is generally desirable to make the pigmented ink jet ink inconcentrated form. The concentrated pigmented ink jet ink, which issubsequently diluted to the appropriate concentration for use in the inkjet printing system. This technique permits preparation of a greaterquantity of pigmented ink from the equipment. If the pigment dispersionis made in a solvent, it is diluted with water and optionally othersolvents to obtain the appropriate concentration. If the pigmentdispersion is made in water, it is diluted with either additional wateror water soluble solvents to make a pigment dispersion of the desiredconcentration. By dilution, the ink is adjusted to the desiredviscosity, color, hue, saturation density, and print area coverage forthe particular application.

In the case of organic pigments, the ink may contain up to approximately30% pigment by weight, but will generally be in the range ofapproximately 0.1 to 15%, preferably approximately 0.1 to 8%, by weightof the total ink composition for most thermal ink jet printingapplications. If an inorganic pigment is selected, the ink will tend tocontain higher weight percentages of pigment than with comparable inksemploying organic pigment, and may be as high as approximately 75% insome cases, because inorganic pigments generally have higher specificgravities than organic pigments. The acrylic block polymer is present inthe range of approximately 0.1 to 30% by weight of the total inkcomposition, preferably in the range of approximately 0.1% to 8%. If theamount of polymer becomes too high, the ink color density will beunacceptable and it will become difficult to maintain desired inkviscosity. Dispersion stability of the pigment particles is adverselyaffected if insufficient acrylic block copolymer is present. The amountof aqueous carrier medium plus penetrant is in the range ofapproximately 70 to 99.8%, preferably approximately 94 to 99.8%, basedon total weight of the ink when an organic pigment is selected,approximately 25 to 99.8%, preferably approximately 70 to 99.8% when aninorganic pigment is selected and 80 to 99.8% when a dye is selected.

Other additives, such as surfactants, biocides, humectants, chelatingagents, and viscosity modifiers may be added to the ink. Optionally,other acrylic and non-acrylic polymers, may be added to improveproperties such as water fastness and smear resistance.

Jet velocity, separation length of the droplets, drop size, and streamstability are greatly affected by the surface tension and the viscosityof the ink. Pigmented ink jet inks suitable for use with ink jetprinting systems should have a surface tension in the range of about 20dyne/cm to about 70 dyne/cm and, more preferably, in the range 30dyne/cm to about 70 dyne/cm. Acceptable viscosities are no greater than20 cP, and preferably in the range of about 1.0 cP to about 10.0 cP. Theink has physical properties compatible with a wide range of ejectingconditions, i.e., driving voltage and pulse width for thermal ink jetprinting devices, driving frequency of the piezo element for either adrop-on-demand device or a continuous device, and the shape and size ofthe nozzle. The inks have excellent storage stability for a long periodand do not clog in an ink jet apparatus. Fixing the ink on the imagerecording material, such as, paper, fabric, film, etc., can be carriedout rapidly and accurately. An ink prepared by mixing an aqueous pigmentdispersion with the subject cosolvent, hydroxypivalyl hydroxypivalate(HPHP), diethylene glycol solvent and a surfactant dries on bond testpaper in less than 15 seconds. It also shows superior first drop decapof ca. 80 second compared to most pentrants which give values of 30-60seconds. A 32nd drop decap time of 30-45 minutes is much superior tocommon penetrants which give values in the 2-5 minute time frame. Theink showed only an increase of 2 nm on a Brookhaven RI-90 Particle SizeAnalyser after 4 consecutive temperature cycles at -20° and 60° C. Thisis well within experimental error. Changes less than 20 nm areconsidered acceptable.

The printed ink images have clear color tones, high density, excellentwater resistance and lightfastness. Furthermore, the ink does notcorrode parts of the ink jet printing device it comes in contact with,and it is essentially odorless, and non-toxic.

EXAMPLES

The following examples serve to illustrate the practice of the presentinvention.

EXAMPLE 1

Ink was prepared as follows:

Dispersant Preparation:

A block copolymer of n-butyl methacrylate and methacrylic acid wasprepared as follows:

3750 grams of tetrahydrofuran, 7.4 grams of p-xylene, were added to a12-liter flask equipped with a mechanical stirrer, thermometer, nitrogeninlet, drying tube outlet, and addition funnels. The catalyst,tetrabutyl ammonium m-chlorobenzoate, 3.0 ml of a 1.0M solution inacetonitrile, was then added to the flask. 291.1 grams (1.25M) of aninitiator, 1,1-bis(trimethylsiloxy)-2-methyl propene, were injected.Feed I which consisted of tetrabutyl ammonium m-chlorobenzoate, and 3.0ml of a 1.0M solution in acetonitrile, was started and added over 150minutes. Feed II which consisted of 1976 gm (12.5M) trimethylsilylmethacrylate, was started at 0.0 minutes and added over 35 minutes. Onehundred and eighty minutes after Feed II was completed over 99% of themonomers had reacted. Feed III, which consisted of 1772 gm (12.5M) butylmethacrylate, was started and added over 30 minutes.

At 400 minutes, 780 grams of dry methanol were added to the abovesolution and distillation commenced. During the first stage ofdistillation, 1300.0 grams of material with a boiling point below 55° C.were removed from the flask. The theoretical amount ofmethoxytrimethylsilane, having a boiling point of 54° C. (BP=54° C.) tobe removed was 1144.0 grams. Distillation continued during the secondstage while the boiling point increased to 76° C. 5100 gms ofisopropanol were added during the second stage of distillation. A totalof 7427 grams of solvent were removed. The resultant resin solution wasused directly in the next step. It contained 55.8% solids and had aneutralization equivalent of 4.65 milliequivalents of potassiumhydroxide per gram of solids.

Neutralization of Dispersant:

The following materials were added to a 1000 ml cylindrical polyethylenebottle:

200.0 grams dispersant solution

174.4 grams 15% potassium hydroxide

137.6 grams deionized water

The mixture was tumbled on a roller mill for 3-4 hours and thenmagnetically stirred for 16-20 hours to give a slightly cloudy solution.

Preparation of Pigment Dispersion:

The following materials were added to a 1 liter beaker:

78.3 grams deionized water

66.7 grams neutralized dispersant solution

3.0 grams 15% potassium hydroxide

The solution was mechanically stirred while 20.0 grams of carbon blackpigment, FW 18 (Degussa Corp., Ridgefield Park, N.J. 07660) were addedin portions. Stirring was continued for 30 minutes. The contents werethen added to a Mini Motormill 100 (Eiger Machinery Inc., Bensenville,Ill. 60106) with another 32 grams of deionized water as a rinse. Thecontents were milled at 3500 rpm for one hour. The yield was 190.8grams. The pH was 7.6. The particle size was 138 nm as determined by aBrookhaven BI-90 Particle analyser (Brookhaven Instruments Corp.,Holtsville, N.Y. 11742).

Preparation of Inks:

The following ingredients were combined and added with magnetic stirringover 10-15 minutes to 22.5 grams of pigment dispersion:

2.6 grams diethylene glycol (Aldrich Chemical Co. Inc., Milwaukee, Wis.53233)

2.6 grams comparative cosolvent or ester diol or amide diol 0.5 gramsSilwet® L-77 (Union Carbide Corp., Danbury, Conn. 06817)

37.2 grams deionized water.

                  TABLE 1                                                         ______________________________________                                        Control Cosolvent and Ester                                                   Diol Cosolvent Identification                                                 All cosolvents were obtained from Aldrich Chemical                            Co. Inc., Milwaukee, WI 53233 unless otherwise stated.                        A cosolvent was added to the ink as previously                                discussed. The cosolvents are identified as follows:                          Comparative Cosolvents                                                        ______________________________________                                                                Control #                                             Butyl Carbitol ® (Union Carbide                                                                   1                                                     Corp., Danbury, CT)                                                           Dowanol TBH, (Dow Chemical,                                                                           2                                                     Midland MI 48640)                                                             Dipropylene Glycol      3                                                     Hexylene Glycol         4                                                     Neopentyl Glyco         5                                                     Triethylene Glycol      6                                                     Glycerol                7                                                     5-Hexene-1,2-diol       8                                                                             Example #                                             Hydroxypivalyl Hydroxypivalate                                                                        1                                                     (Eastman Chemical Co., Kingsport, TN 37662)                                   ______________________________________                                    

                  TABLE 2                                                         ______________________________________                                        Drying Times                                                                  Drying times were obtained by printing rapidly a                              series of solid patterns on a Hewlett Packard DeskJet                         printer (Hewlett Packard Co., Palo Alto CA 94303) and                         immediately wiping them in 15 second increments, and                          recording the time in which the printed ink would no                          longer smear. A semiabsorbent paper, Gilbert Bond (Mead                       Co., Dayton, OH) was used.                                                           Sample  Dry Time, seconds                                              ______________________________________                                               Control 1                                                                             <15                                                                   Control 2                                                                             <15                                                                   Control 3                                                                             15-30                                                                 Control 4                                                                             15-30                                                                 Control 5                                                                             15-30                                                                 Control 6                                                                             15-30                                                                 Control 7                                                                             30-45                                                                 Control 8                                                                             <15                                                                   Example 1                                                                             <15                                                            ______________________________________                                    

                  TABLE 3                                                         ______________________________________                                        Decap Times                                                                   Decap times were obtained on a Deskjet printer that                           had been altered so that the ink cartridge would not be                       vacuum suctioned nor spit into a spitoon. The last time                       interval that the particular drop did not fail is recorded.                                    5th        32nd   Drop                                       Sample     1st   seconds    minutes                                                                              minutes                                    ______________________________________                                        Control    1     90         1      1.5                                                   2     60         1      3.0                                                   3     55         2      5.0                                                   4     40         0.5    1.5                                                   5     35         1      1.5                                                   6     40         1      1.1                                                   7     25         0.75   1.0                                        Example    1     80         3-4    30-45                                      ______________________________________                                    

                  TABLE 4                                                         ______________________________________                                        Dispersion Stability                                                          Dispersion stability was obtained by subjecting 15                            grams of ink to four temperature cycles, each consisting                      of 4 hours at -20° C. and 4 hours at 60° C. Particle sizes      were measured on a Brookhaven BI-90 (Brookhaven                               Instruments Corp., Holtsville, NY 11742) before and after cycling.                       Change in Particle Size, delta                                     Sample     nanometers                                                         ______________________________________                                        Control #                                                                     1          36                                                                 2          22                                                                 3          4                                                                  4          2                                                                  5          4                                                                  6          3                                                                  7          -5                                                                 8          12                                                                 Example #                                                                     1          2                                                                  ______________________________________                                    

What is claimed is:
 1. An aqueous ink jet ink composition comprising:(a)an aqueous carrier medium, (b) a pigment dispersion or dye; and (c) apenetrant which is an ester diol or amide diol compound having asolubility in water of at least 4.5 parts in 100 parts of water at 25°C. and represented by the formula: ##STR4## wherein R'=--CH₃, --C₂ H₅,--C₃ H₇, or --C₄ H₉ and R"=--CH₃, --C₂ H₅, or --C₃ H₇ and X=O or N--Ywherein Y=H, CH₃, CH₂ CH₃ or CH₂ CH₂ OH.
 2. The ink composition of claim1 wherein the pigment dispersion comprises a pigment and a dispersant.3. The aqueous ink jet ink of claim 1 or 2 wherein the penetrant is anester diol represented by the formula: ##STR5## wherein R'=--CH₃, --C₂H₅, --C₃ H₇, and --C₄ H₉, andR"=--CH₃, --C₂ H₅, or --C₃ H₇.
 4. Theaqueous ink jet ink of claim 3 wherein the ester diol is neopentylglycol hydroxypivalate and is represented by the formula: ##STR6## 5.The pigmented ink of claim 2 wherein the dispersant is a polymericdispersant.
 6. The pigmented ink of claim 5 wherein the polymericdispersant is an AB or BAB block copolymer wherein(a) the A segment is ahydrophobic homopolymer or copolymer of an acrylic monomer having theformula: CH₂ ═C(X)(Y) wherein X is H or CH₃ ; and Y is C(O)OR₁, C(O)NR₂R₃, or CN, wherein R₁ is an alkyl, aryl, or alkylaryl group having 1 to20 carbon atoms, and R₂ and R₃ are hydrogen or an alkyl, aryl, oralkylaryl group having 1 to 9 carbon atoms; said A segment having anaverage molecular weight of at least approximately 300 and being waterinsoluble; and (b) the B segment is a hydrophilic polymer, or saltthereof, of(1) an acrylic monomer having the formula CH₂ ═C(X) (Y₁),wherein X is H or CH₃ ; and Y₁ is C(O)OH, C(O)NR₂ R₃, C(O)OR₄ NR₂ R₃ orC(OR₅); wherein R₂ and R₃ are hydrogen or an alkyl, aryl, or alkylarylgroup having 1 to 9 carbon atoms; R₄ is an alkyl diradical having 1 to 5carbon atoms; and R5 is an alkyl group having 1 to 20 carbon atoms andoptionally containing one or more hydroxyl or ether groups; or (2) acopolymer of the acrylic monomer of (1) with an acrylic monomer havingthe formula:

    CH.sub.2 ═C(X) (Y)

where X and Y are the substituent groups defined for the A segment; theB segment having an average molecular weight of at least approximately300 and being water soluble.
 7. The pigmented ink of claim 6 wherein thepolymeric dispersant is an AB or BAB block copolymer wherein the Asegment of said block copolymer is a homopolymer or copolymer preparedfrom at least one monomer selected from the group consisting of methylmethacrylate, ethyl methacrylate, propyl methacrylate, butylmethacrylate, n-butyl methacrylate, hexyl methacrylate, 2-ethylhexylmethacrylate, octyl methacrylate, lauryl methacrylate, stearylmethacrylate, phenyl methacrylate, benzyl methacrylate, hydroxyethylmethacrylate, hydroxypropyl methacrylate, 2-ethoxyethyl methacrylate,methacrylonitrile, 2-trimethylsiloxyethyl methacrylate, glycidylmethacrylate, p-tolyl methacrylate, sorbyl methacrylate, methylacrylate, ethyl acrylate, propyl acrylate, butyl acrylate, hexylacrylate 2-ethylhexyl acrylate, octyl acrylate, lauryl acrylate, stearylacrylate, phenyl acrylate, benzyl acrylate, hydroxyethyl acrylate,hydroxypropyl acrylate, acrylonitrile, 2-trimethyl-siloxyethyl acrylate,glycidyl acrylate, p-tolyl acrylate, and sorbyl acrylate.
 8. Thepigmented ink of claim 7 wherein the A segment of said block copolymeris a homopolymer or copolymer prepared from methyl methacrylate, n-butylmethacrylate, 2-ethylhexyl methacrylate or a copolymer of methylmethacrylate with butyl methacrylate.
 9. The pigmented ink of claim 8wherein the A segment is a homopolymer of n-butyl methacrylate.
 10. Thepigmented ink of claim 6 wherein the B segment of said block copolymeris a homopolymer or copolymer prepared from at least one monomerselected from the group consisting of methacrylic acid, acrylic acid,dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate,t-butylaminoethyl methacrylate, dimethylaminoethyl acrylate,diethylaminoethyl acrylate, dimethylaminopropyl methacrylamide,methacrylamide, acrylamide, and dimethylacrylamide.
 11. The pigmentedink of claim 10 wherein the B segment of said block copolymer is ahomopolymer of methacrylic acid or dimethylaminoethyl methacrylate. 12.The pigmented ink of claim 11 wherein the B segment of said blockcopolymer is a homopolymer of methacrylic acid.
 13. The pigmented ink ofclaim 2 or 5 wherein said ink contains approximately 0.1 to 15% pigment,0.1 to 30% dispersant, and 55 to 99.8% of a combination of aqueouscarrier medium plus ester diol or amide penetrant.
 14. The pigmented inkof claim 13 wherein the aqueous carrier medium comprises water and atleast one water soluble organic solvent.
 15. The pigmented ink of claim14 wherein the combination of aqueous carrier medium plus penetrantcontains from 30% water/70% solvent/ester diol mixture to 95% water /5%solvent/ester diol mixture.
 16. The pigmented ink of claim 15 whereinthe solvent/ester diol mixture contains 15-95% ester diol.
 17. Thepigmented ink of claim 16 wherein the solvent/ester diol mixturecontains 25-75% ester diol.
 18. The pigmented ink of claim 13 whereinsaid ink contains approximately 0.1 to 8% pigment, 0.1 to 8% dispersant,and 84 to 99.8% of a combination of aqueous carrier medium plus esterdiol.
 19. The ink of claim 1 wherein said ink contains up to 20% dye,and 80 to 99.8% of a combination of aqueous carrier medium pluspenetrant.
 20. The ink of claim 19 wherein said aqueous carrier mediumplus penetrant contains 35% ester diol.
 21. The ink of claims 1 or 2wherein the aqueous carrier medium is a mixture of water and at leastone water soluble organic solvent having at least 2 hydroxyl groups. 22.The pigmented ink of claim 2 wherein the pigment particles have a medianpartial size of approximately 0.01 to 1 micron.
 23. The pigmented ink ofclaim 6 wherein the B segment of said block copolymer is neutralizedwith a neutralizing agent selected from the group consisting of organicbases, alkanolamines, alkali metal hydroxides, and mixtures thereof. 24.The ink composition of claim 1 or 2 wherein a surfactant is present. 25.The ink composition of claim 24 wherein the surfactant is apolyalkyleneoxide modified polydimethylsiloxane.